What media type is selected for this paper? Is it the same media type you used previously when printing successfully? Possible solutions:
1) Increase the vacuum strength to Standard or Strong
2) Increase the head height one level at a time
3) Try to put a very slight reverse curl in the paper
Default for each of the two settings is "Automatic". I don't know if that means that there is a mechanism for the printer to determine these, or if it means there is a hidden default in the driver. Haven't been able to determine this yet.
Check pages 49-50 of the printed reference guide that came with the printer for more details.
See also the Wiki:http://www.canonipf5000.wikispaces.com
There is a discussion section there now (accessible from the Main page) and you might be able to get some help there.